The field of the invention is machine tools and the invention relates more particularly to devices for affixing work pieces on a tool, such as a milling machine, so that the work piece is held at a known desired angle.
Milling parts in specific angles and with accuracy on the X-Z and Y-Z planes requires the use of special fixtures, such as special fixed angle fixtures, tilting tables, and swivel angle plates, sine tables and rotary tables.
Special fixed angle fixtures are usually homemade fixtures made to set and clamp a part to be machined and the fixture is fixed to a specific angle. Such fixtures are very expensive because they have to be redone and redesigned for any other angle and/or any other part. Fixtures of this type can be very accurate (plus or minus 30 seconds), but they are not versatile and not very quick to set up.
Tilting tables and swivel angle plates are available. They are very standard and more versatile than special fixed angle fixtures because other standard fixtures, such as indexers, clamp holders, vises, and rotary tables can be mounted on top. This type of table is usually built with two pieces, one bottom plate to be clamped to the table of the machine, and the other a top plate that swivels or tilts up and down. These fixtures are not too expensive but do not provide great accuracy (with one degree at best). The angle is set visually using graduated angular scales that are part of the fixture or using external protractors. They are versatile, not too accurate and not too quick to set up.
Sine tables are similar to tilt tables, but they are stronger and very accurate. These tables are also built on two pieces like the tilting tables and swivel angle plates. In this case, both plates are hinged on one end and the angle is achieved by using gauge blocks. Some calculations in trigonometry are required to define the height of the gauge blocks. These types of fixtures are versatile, very accurate, not too quick to set up, and expensive.
Rotary tables, either manual or CNC controlled, can be mounted on machines vertically and, by using angle plates, such as indexers, clamp holders, vises, and rotary tables, can be mounted on top of the angle plate and the angles can be obtained by the rotation of the rotary table itself. In general, these types of fixtures are very versatile, very accurate, very expensive, and the set up is very time consuming.
There is, thus, a need for a tilt table which is quick to set up, accurate, flexible and versatile.